The human auditory system has been increasingly stressed to tolerate high noise levels to which it had hitherto been unexposed. Recently, human knowledge of the causes of hearing damage have been researched intensively, and models for predicting hearing loss have been developed and verified with empirical data from decades of scientific research. And yet it can be strongly argued that the danger of permanent hearing damage is more present in our daily lives than ever, and that sound levels from personal audio systems in particular (e.g., from portable audio devices), live sound events, and the urban environment are a ubiquitous threat to healthy auditory functioning across the global population. Music reproduction levels and urban noise are antagonistic; we play our personal audio devices louder to hear over the traffic noise. And use of personal audio devices is rapidly increasing, especially in the younger generation who are suffering permanent hearing damage at increasingly younger ages.
Noise is a constant in industrialized societies, given the ubiquity of external sound intrusions, such as people talking on their cell phones, blaring music in health clubs, or the constant hum of HVAC systems in schools and office buildings. To combat the undesired cacophony, consumers are arming themselves with portable audio playback devices to drown out intrusive noise. The majority of devices providing the consumer with audio content do so using insert (or in-ear) earbuds, which deliver sound directly to the ear canal, generating levels sufficient to perceptually mask background noise even though the earbuds provide little to no ambient sound isolation. With earbuds, personal audio reproduction levels can reach in excess of 100 dB; enough to exceed recommended daily sound exposure levels in less than a minute and to cause permanent acoustic trauma. Furthermore, rising population densities have continually increased sound levels in society. According to research, 40% of the European community is continuously exposed to transportation noise of 55 dBA and 20% are exposed to greater than 65 dBA. This level of 65 dBA is considered by the World Health Organization to be intrusive or annoying, and as mentioned, can lead to users of personal audio devices increasing reproduction level to compensate for ambient noise.
Noise exposure can generate auditory fatigue, possibly compromising a person's listening abilities. On a daily basis, people are exposed to various environmental sounds and noises within their environment, such as the sounds from traffic, construction, and industry. Some of the sounds in the environment may correspond to warnings, such as those associated with an alarm or siren. A person that can hear the warning sounds can generally react in time to avoid danger. In contrast, a person that cannot adequately hear the warning sounds, or whose hearing faculties have been compromised due to auditory fatigue, may be susceptible to danger.
Environmental noise can mask warning sounds and impair a person's judgment. Moreover, when people wear headphones to listen to music, or engage in a call using a telephone, they can effectively impair their auditory judgment and their ability to discriminate between sounds. With such devices, the person is immersed in the audio experience and generally less likely to hear warning sounds within their environment. In some cases, the user may even turn up the volume to hear their personal audio over environmental noises. This can put the user in a compromising situation since they may not be aware of warning sounds in their environment. It also puts them at high sound exposure risk which can potentially cause long term hearing damage.
A need therefore exists for enhancing the user's ability to hear warning sounds in the environment and control audio without compromising hearing.